GENETIC MUTATION

 


A genetic mutation is a change in the sequence of your DNA. Your DNA sequence provides your cells with the information they need to work properly. If part of your DNA sequence is incorrect, missing, or damaged, you may have symptoms of a genetic disorder.

WHEN DOES GENETIC MUTATION OCCURS?


Genetic mutations happen during cell division when your cells divide and make copies of themselves. There are two kinds of cell division:


Mitosis: The process by which new cells are produced for the body. While mitosis is under way, your genes are informing your cells to divide into two by making an exact copy of your chromosomes.

Meiosis: The process of producing egg and sperm cells for the next generation. In meiosis, the chromosomes make a copy with half as many as the original had, from 46 to 23. That is how you were able to get your genetic material equally from each parent.

HOW DO GENETIC MUTATION MUTATIONS OCCUR?


Cell division causes genetic alterations. When your cells replicate, your body's instruction manual gets copied out word for word by hand. This is why there's such a huge potential for error during cell division: because your cells can substitute—or replace—letters when they're copying. If you have a genetic mutation, your cells may not be able to read your genetic instruction manual, or it might be missing or contain extra stuff. All this can lead to your cells not functioning properly.

WHERE ARE GENES STORED?


The genes are located on thread-like structures called chromosomes. Chromosomes are located within every cell of your body. Your body contains trillions of cells that all make you 'you'.

TYPES OF MUTATION


A germline mutation is a gene alteration that occurs in the reproductive cells of a parent, either the egg or the sperm, thus altering their child's genetic makeup.

A somatic mutation is an alteration in a gene that occurs after conception, during the growth of the embryo that may become a newborn.

SOME MUTATIONS PASSED FROM PARENTS TO CHILD

Autosomal Dominant: A disorder is autosomal dominant if only one parent needs to pass on the genetic mutation for a child to inherit the mutation. One example of a disorder which exhibits this pattern of inheritance is Marfan syndrome.

Autosomal recessive: means that the child must inherit an exact gene mutation from both parents to express the mutation. One example of a disorder with this type of inheritance is sickle cell disease.

X-Linked Dominant Inheritance: Babies are either male or female depending on the presence of the X chromosome. A young child only needs to get one mutated X chromosome from one parent for the youngster to inherit the mutation. One example of a disorder caused by this inheritance pattern is called fragile X syndrome.

X-linked recessive: If only the father has the mutation, then all female kids will be carriers; no male offspring will have the disease. If only mother has the mutation, then the female offspring are 50% likely to be carriers while male offspring are 50% likely to have the disease. Lastly, if the mutation is contained in both parents, then the cases of the disease shall be present in 50% of the male children while 100% of the female offspring. Color blindness is one example of a disorder inherited in this pattern.

X-linked: Babies are assigned as male, or female based on their X chromosome. Mutations on the X chromosome can pass in a dominant or recessive pattern although not all patterns indicate how the child inherited the mutation from their parents. Thrombocytopenia is an example of a condition that follows this inheritance pattern.

Y-linked: Only boys have the Y chromosome and thus can inherit this type. Only one Y chromosomal mutation needs to be passed on to the child to inherit the mutation. Webbed toes are a condition inherited in this way.

Codominant: A gene has two parts. They normally work together to make a trait. They sometimes, however act alone in producing variations of a trait. Alpha-1 antitrypsin deficiency is an example of a disorder that leads to this pattern of inheritance.

Mitochondria: Mitochondria are organelles that supply energy to the cell. During fertilization, when the two cells merge, only the mitochondria from the egg survive. This means the source of every mitochondrial DNA—and thus, maternal DNA—in the embryo is from the egg. That is why mitochondrial inheritance is sometimes referred to as maternal inheritance. One example of a disorder inherited this way is Leber hereditary optic neuropathy, or sudden vision loss.

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